Semiconductor devices are commonly found in modern electronic products. Semiconductor devices vary in the number and density of electrical components. Discrete semiconductor devices generally contain one type of electrical component, e.g., light emitting diode (LED), small signal transistor, resistor, capacitor, inductor, and power metal oxide semiconductor field effect transistor (MOSFET). Integrated semiconductor devices typically contain hundreds to millions of electrical components. Examples of integrated semiconductor devices include microcontrollers, microprocessors, charged-coupled devices (CCDs), solar cells, and digital micro-mirror devices (DMDs).
Semiconductor devices perform a wide range of functions such as signal processing, high-speed calculations, transmitting and receiving electromagnetic signals, controlling electronic devices, transforming sunlight to electricity, and creating visual projections for television displays. Semiconductor devices are found in the fields of entertainment, communications, power conversion, networks, computers, and consumer products. Semiconductor devices are also found in military applications, aviation, automotive, industrial controllers, and office equipment.
Semiconductor devices exploit the electrical properties of semiconductor materials. The atomic structure of semiconductor material allows its electrical conductivity to be manipulated by the application of an electric field or base current or through the process of doping. Doping introduces impurities into the semiconductor material to manipulate and control the conductivity of the semiconductor device.
A semiconductor device contains active and passive electrical structures. Active structures, including bipolar and field effect transistors, control the flow of electrical current. By varying levels of doping and application of an electric field or base current, the transistor either promotes or restricts the flow of electrical current. Passive structures, including resistors, capacitors, and inductors, create a relationship between voltage and current necessary to perform a variety of electrical functions. The passive and active structures are electrically connected to form circuits, which enable the semiconductor device to perform high-speed calculations and other useful functions.
Semiconductor devices are generally manufactured using two complex manufacturing processes, i.e., front-end manufacturing, and back-end manufacturing, each involving potentially hundreds of steps. Front-end manufacturing involves the formation of a plurality of die on the surface of a semiconductor wafer. Each semiconductor die is typically identical and contains circuits formed by electrically connecting active and passive components. Back-end manufacturing involves singulating individual semiconductor die from the finished wafer and packaging the die to provide structural support and environmental isolation. The term “semiconductor die” as used herein refers to both the singular and plural form of the words, and accordingly can refer to both a single semiconductor device and multiple semiconductor devices.
One goal of semiconductor manufacturing is to produce smaller semiconductor devices. Smaller devices typically consume less power, have higher performance, and can be produced more efficiently. In addition, smaller semiconductor devices have a smaller footprint, which is desirable for smaller end products. A smaller semiconductor die size can be achieved by improvements in the front-end process resulting in semiconductor die with smaller, higher density active and passive components. Back-end processes may result in semiconductor device packages with a smaller footprint by improvements in electrical interconnection and packaging materials.
A semiconductor die is commonly mounted over a substrate with an underfill material deposited between the semiconductor die and substrate, as shown in FIG. 1a. Semiconductor die 10 is mounted to substrate 12 with bumps 14. A dispensing needle 16 injects underfill material 18 into area 20 between semiconductor die 10 and substrate 12. Dispensing needle 16 moves between reference point 20 and reference point 22 across a width of semiconductor die 10 while injecting underfill material 18 into area 20, as shown in FIG. 1b. 
The underfill material 18 is known to build up unevenly in area 20 due to an non-uniform flow rate. Bumps 14 are disposed around a perimeter of semiconductor die 10. No bumps are formed within central region 26 of semiconductor die site 28. The presence of bumps 14 around the perimeter of semiconductor die 10 reduces the volume to fill in that area and increases the effective flow rate of underfill material 18 around the bumps. The portion of area 20 without bumps 14, i.e., central region 26, has more volume to fill, which reduces the effective flow rate of underfill material 18. The flow rate of underfill material 18 around bumps 14 is greater than the flow rate of underfill material 18 in central region 26, as shown in FIG. 1b. The non-uniform flow rate of underfill material 18 can cause bleed-out around semiconductor die 10 and form voids in the underfill material. The voids in underfill material 18 can reduce the reliability of semiconductor die 10.